Field of the Invention
The present invention relates to a sound processing apparatus and a sound processing method.
Description of Related Art
A transfer function indicating transfer characteristics when sound generated from a sound source propagates to a sound collecting unit might be used to process a collected sound signal. The transfer function is used for the purpose of correction of sound quality (such as equalizing), reverberation reduction, noise reduction, estimation of a sound source direction or a sound source position, and the like.
Accordingly, various methods of calculating a transfer function have been proposed in the related art.
For example, a sound system described in Japanese Patent No. 4482247 sequentially outputs a plurality of predetermined band noise signals of different frequency bands from a speaker, filters detected noise signals detected by microphones disposed in a sound field of the speaker by the use of a plurality of predetermined band filters, and analyzes the filtered detected noise signals for each of a plurality of frequency bands. The sound system inputs the band noise signals and the detected noise signals to a transfer function calculating unit, calculates transfer functions from the speaker to the microphones, and corrects the calculated transfer functions depending on the passing characteristics of the band filters.
In the sound system described in Japanese Patent No. 4482247, the positional relationships between the microphones and the sound source is known and it is necessary to use a measuring sound source for the aforementioned detected noise signals separately from a hearing sound source. Accordingly, a method of estimating the positional relationships between the microphones and the sound sources using collected sound signals without using the measuring sound source has been proposed.
For example, a sound source position estimating method described in Japanese Unexamined Patent Application, First Publication No. 2012-161071 includes calculating an inter-channel time difference of sound signals, predicting current sound source state information from previous sound source state information which is sound source state information including a sound source position and a microphone position, and estimating the sound source state information so as to reduce an error between the calculated inter-channel time difference of the sound signals and a time difference based on the sound source state information.